Reforming of a hydrocarbon fraction is a common method for increasing the octane number and concentration of aromatics in the hydrocarbon fraction. Typical reforming catalysts comprise a hydrogenation-dehydrogenation component supported on a porous solid carrier. Typical catalysts include platinum on alumina with or without such promoters as rhenium, tin, iridium, etc. Typical reaction conditions include a temperature within the range from 700.degree. to 1050.degree. F., a pressure generally within the range from 25 to 1000 psig, a liquid hourly space velocity from 0.01 to 20, and a hydrogen to hydrocarbon molar ration from 0.5 to 20.
In recent years, due to the required phase down of lead in motor gasoline, it has become increasingly necessary to produce a reformate having higher and higher octane number for blending to make motor gasoline. To make this higher octane reformate, the reforming zone must be operated at increasingly severe conditions which in turn means increasingly reduced yields of the reformate. Refiners are constantly searching for methods which will allow them to increase the yield of C.sub.5 + reformate while allowing them to maintain a given octane number.
Occasionally it is desirable to reform a particular fraction of the naphtha feedstock, for example, when it is desired to obtain a reformate enriched in a benzene-toluenexylene (BTX) fraction or at least one of the BTX components. After removal of the BTX-precursor stream, usually a heartcut of the naphtha feedstock, standard practice has been to separately reform the remaining light naphtha and heavy naphtha fractions at reforming conditions tailored specifically to the optimum reforming of each fraction. However, we have discovered a process which permits recovery of a surprisingly high yield of C.sub.5 + reformate compared to that known process.